Growth characteristics and wear properties of micro-arc oxidation coating on Ti-6Al-4V with different laser texture shapes

Abstract

Poor wear properties severely limit the field of application and service life of titanium alloys. Three kinds of textures (dimple, groove and mesh) were prepared by laser texturing technique and compounded with micro-arc oxidation treatment to improve the tribological properties of titanium alloys in this study. The coatings' morphology, structure, and composition were characterized, and their antiwear properties were analyzed. The results show that the proportion of rutile phase in the coating increases with increasing textured area rate and that the textured edge coating has higher Si and P content, with increased thickness and densities. In terms of friction properties, the dimpled texture shows the best friction properties when textured alone, with a 28.6 % decrease in the average coefficient of friction compared to the substrate; in contrast, the meshed texture shows the best friction properties after the micro-arc oxidation treatment, with a 76.2 % decrease in the average coefficient of friction compared to the substrate. Studies have shown that laser texturing can reduce wear by retaining abrasive debris. However, laser texturing alone does not provide a significant increase in hardness at the edge location, which is more susceptible to damage during wear, leading to more severe wear. The “tip effect” encourages the growth of a micro-arc oxide layer, and the resulting hardness of the layer helps protect the texture structure from damage. The synergistic effect of the texture and the rough, hard structural features of the coating itself enhances the wear resistance of the composite coating.